Decomposers play a crucial role in a biotic community for several reasons:

Now, let's discuss the concept of a food chain and the unidirectional flow of energy:

A food chain is a linear representation of the flow of energy from one organism to another within an ecosystem. It describes the transfer of energy as organisms consume other organisms for sustenance. In a typical food chain, the primary producers (such as plants) are consumed by herbivores (plant-eating organisms), which are then consumed by carnivores (meat-eating organisms), and so on. Each organism in the chain is classified based on its position and feeding habits.

The flow of energy in a food chain is unidirectional, meaning it moves in one direction only. This occurs due to the laws of thermodynamics, specifically the second law of thermodynamics. The second law states that energy tends to disperse or spread out, resulting in a decrease in the quality of available energy over time.

As energy is transferred from one organism to another through consumption, some energy is lost at each trophic level in the form of heat, metabolic waste, and inefficiencies in energy conversion. This loss of energy limits its transfer to higher trophic levels. Consequently, energy cannot flow in reverse within the food chain, and it is primarily channeled from lower trophic levels to higher trophic levels.

The unidirectional flow of energy ensures that energy is continually entering the ecosystem through primary producers (via photosynthesis or chemosynthesis) and leaving the ecosystem as heat or waste products. This energy flow sustains the functioning and productivity of the ecosystem while maintaining the overall energy balance within it.

A food chain consists of levels known as trophic levels, which are defined by the energy source of the organisms belonging to the particular level. A food chain is a part of a food web and is not as complex as a food web. The chain follows a straight line path of a particular animal. Food chains of different organisms can be determined based on the length of the chain. Chain length is the number of links between the organism and the base of the chain. The amount of energy transferred from one link to another decreases as the length of the food chain decreases because only 10% of the total energy from one level is transferred to the next level while the rest is used by the organism at that level.

The flow of energy and biomass through a food chain is essential for the survival of most species, and the removal of one element of the food chain can lead to the extinction of the entire species. The basis of all food chains are producers who use a primary source of energy (the sun or chemical reactions) to produce food usable by living organisms.

Dr Fatemeh Gharahdaghigharahtappeh and Dr Abdullah S. Seddiek thank you for your contribution to the discussion

The flow of energy in the ecosystem is unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis. During the transfer of energy through successive trophic levels in an ecosystem, there is a loss of energy all along the path. The energy stored in the plants through photosynthesis is transferred to herbivores that feed on the plants. From herbivores, energy is transferred to carnivores that feed on them. So the direction of the flow of energy is from the sun to the carnivores. The flow of energy in food chain in unidirectional because the sun is the only source of energy for all ecosystems on earth. Then the energy is captured by the autotrophs does not revert back to the sun. Therefore, in the food chain, the energy moves progressively through various trophic levels. Energy flows through an ecosystem in only one direction. Energy is passed from organisms at one trophic level or energy level to organisms in the next trophic level. Decomposers play a critical role in the flow of energy through an ecosystem. They break apart dead organisms into simpler inorganic materials, making nutrients available to primary producers. Most important decomposers are bacteria, fungi, protozoa, annelid worms and arthropods. Decomposers are the biotic factor in the environment that decomposes the plants, animals, and feces of animals.